MPLS cisco QOS VPN full mpls advanced

Advanced Developments in MPLS QoS Bruce Davie bsd@cisco.com MPLS NW Internal 05/01 â 2001, Cisco Systems, Inc Agenda DS-TE Diffserv-aware traffic engineering & MPLS Guaranteed Bandwidth services • “QoS Transparency” © 2001, Cisco Systems, Inc Diffserv-aware Traffic Engineering (DS-TE) 2302 Presentation_ID 2000, Cisco Systems, Inc.Systems, Inc MPLS NW Internal â 05/01 â 2001, Cisco Terminology DS-TE: Diffserv-aware Traffic Engineering A set of protocol extensions to existing MPLS TE purely in the control plane - no new data plane QoS mechanisms (e.g no per-label queueing) does NOT achieve QoS “guarantee” by itself • Guaranteed Bandwidth Services End-end (or edge-edge) services Built using DS-TE and existing MPLS QoS features (MPLS Diffserv, QPPB, ) © 2001, Cisco Systems, Inc MPLS Traffic Engineering Find route & set-up tunnel for 20 Mb/s from POP1 to POP4 Find route & set-up tunnel for 10 Mb/s from POP2 to POP4 WAN area POP4 POP1 POP POP2 POP POP © 2001, Cisco Systems, Inc Relationship between MPLS TE and QoS • MPLS TE designed to improve backbone efficiency independently of QoS: MPLS TE compute routes for aggregates across all PHBs MPLS TE performs admission control using “global” bandwidth pool unaware of bandwidth allocated to each queue • MPLS TE and MPLS Diff-Serv: can run simultaneously & independently TE distributes aggregate load Diff-Serv provides QoS differentiation are unaware of each other (e.g., no per-class admission control in TE) © 2001, Cisco Systems, Inc Delay/Load Trade-Off Delay Good Best-Effort Target Data Premium Target Voice Target Utilization 0% α% β % 100% If I can keep EF traffic < α % , I will keep EF delay under M1 ms If I can keep AF1 traffic < β % , I will keep AF1 delay under M2 ms © 2001, Cisco Systems, Inc Motivation for DS-aware TE • Additional constraints to ensure QoS of each class: Good EF behavior requires EF load < α % of link Good AF behavior requires AF load < β % of link • Cannot be enforced by current aggregate TE • Requires Diff-Serv-aware TE Constraint Based Routing per Class with different bandwidth constraints Admission Control per Class over different bandwidth pools (reflecting bandwidth allocated to class queue) © 2001, Cisco Systems, Inc Bandwidth Pools Global TE Bandwidth Pool reflects total link capacity A per-class pool reflects queue capacity A second per-class pool © 2001, Cisco Systems, Inc When is DS-aware TE needed? • Not in uniformly over-provisioned networks Aggregate load is small percentage of link ⇒ EF load will be less than α %; AF1 load will be less than β % • In networks where some parts are not over-provisioned ensures (through routing and admission control) that per-class loads targets are met (e.g EF < α %) example: Global (transcontinental) ISPs • Note: does not “create” bandwidth Use resources on non SPF-path Reject establishment of excess tunnels © 2001, Cisco Systems, Inc 10 VoMPLS using Diff-Serv EF PSTN Call Agent EF/PQ PSTN Voice BE Data If EF load obviously very small compared to every link capacity then just works fine That’s it! © 2001, Cisco Systems, Inc 24 DS-TE Applications: Voice Trunks PSTN Call Agent EF/PQ PSTN Voice BE Data MPLS TE Tunnel for EF (one direction) © 2001, Cisco Systems, Inc 25 Voice over MPLS DS-TE Tunnels • DS-TE tunnels are provisioned to meet expected load between voice gateways • Gateways can re-route calls if insufficient capacity exists on tunnel • Provides hard QoS for voice without relying on overengineering • Maximises amount of voice traffic that can be transported on given set of resources Allows fast reroute of voice â 2001, Cisco Systems, Inc 26 Diff-Serv-aware TE: Conclusions • New work in IETF • Cisco leading with a production implementation • Extensions over existing MPLS TE Routing and admission control on a per -class basis • Allows tighter control of QoS performance for each class Helps solve Diff-Serv provisioning challenge • Enables applications with tight QoS requirements such as “Guaranteed Bandwidth services”, Voice Trunks, Bandwidth Trading,… • Useful in networks that cannot be assumed to be over-engineered everywhere all the time © 2001, Cisco Systems, Inc 27 MPLS QoS Transparency 2302 Presentation_ID 2000, Cisco Systems, Inc.Systems, Inc MPLS NW Internal © 05/01 © 2001, Cisco 28 QoS Transparency • Problem: Provider of VPN service wants to deliver QoS to customers requiring marking of packets Customer doesn’t want packets modified • Approach: Use MPLS header to carry QoS marking without modification of underlying IP packet © 2001, Cisco Systems, Inc 29 Life of a packet CE IP: dscp PE PE MPLS exp MPLS exp MPLS exp MPLS exp MPLS exp IP: dscp IP: dscp IP: dscp CE IP: dscp © 2001, Cisco Systems, Inc 30 Example provider policies • Gold: 64kbps Queue using LLQ, drop excess EXP = 111 • Silver: 32kbps IN, 32kbps OUT Use rate-limit to mark down > 32k, drop > 64k Queue using CBWFQ + WRED EXP = 010 & 110 (IN & OUT) • BE: max 256k (line rate) Queue using CBWFQ EXP = 000 © 2001, Cisco Systems, Inc 31 Main issues • Setting MPLS EXP on imposition • Queuing behavior on egress Arriving label or exposed header? • Scaling provider policies Moving classification to the CE © 2001, Cisco Systems, Inc 32 Imposition behavior • Default is to copy IP Prec to MPLS EXP • DSCP-modifying features (e.g CAR) occur before label imposition • Need another way if customer’s DSCP is not to be modified • Solution: set internal variable(s) from CAR etc, copy to MPLS EXP © 2001, Cisco Systems, Inc 33 Preserving IP DSCP Old: IP: dscp CAR New: IP: dscp MPLS exp Imposition IP: dscp MPLS exp Set EXP IP: dscp CAR VAR=5 © 2001, Cisco Systems, Inc 34 Egress Queuing • Desire to deliver provider’s QoS on last hop to customer • When packet reaches output queue, MPLS label has been removed, exposing IP DSCP • Solution: copy received MPLS EXP to variable, use it for queuing © 2001, Cisco Systems, Inc 35 Moving classification to CE • In general, moving operations to edge improves scaling • Can move provider’s QoS classification policies to CE if provider manages CE, and Can modify IP DSCP, or MPLS labels used on CE-PE link © 2001, Cisco Systems, Inc 36 MPLS labels on CE-PE link • Simplest approach is to use Explicit NULL label • Forwarding information is simply “POP” PE will POP, see IP packet, proceed as normal • New CE behavior to apply Explicit NULL encaps • Store result of provider classification in EXP • Copy popped EXP to pushed EXP at PE © 2001, Cisco Systems, Inc 37 Conclusions • New provider capability: implement QoS features without modifying customer packets Allow customers to set own policies in their networks • MPLS header a convenient place for QoS information • Modest feature enhancements to provide flexible approaches to QoS transparency © 2001, Cisco Systems, Inc 38 ... 2001, Cisco Systems, Inc Relationship between MPLS TE and QoS • MPLS TE designed to improve backbone efficiency independently of QoS: MPLS TE compute routes for aggregates across all PHBs MPLS. .. Systems, Inc 27 MPLS QoS Transparency 2302 Presentation_ID 2000, Cisco Systems, Inc.Systems, Inc MPLS NW Internal © 05/01 © 2001, Cisco 28 QoS Transparency • Problem: Provider of VPN service wants... QoS “guarantee” by itself • Guaranteed Bandwidth Services End-end (or edge-edge) services Built using DS-TE and existing MPLS QoS features (MPLS Diffserv, QPPB, ) © 2001, Cisco Systems, Inc MPLS